In recent years, a method using a crystalline sponge method has attracted attention. When a crystal structure analysis sample is produced using the crystalline sponge method, the crystal structure analysis sample is produced by providing a porous single crystal including of pores and/or voids, bringing the single crystal into contact with a solution of a compound whose molecular structure is to be determined (hereinafter, sometimes referred to as “analysis target compound”) to introduce molecules of the analysis target compound into pores and/or the voids of the single crystal so that the molecules of the analysis target compound are arranged in an ordered manner.
Specifically, Non-Patent Literature 1 discloses a method for producing a crystal structure analysis sample using a porous single crystal of a macromolecular metal complex as a crystalline sponge to introduce a flavonoid and the like into the pores of the porous single crystal.
As described above, by using the crystalline sponge method, it is possible to prepare a crystal structure analysis sample without preparing a single crystal of an analysis target compound. Thus, by using the crystalline sponge method, even when an analysis target compound is liquid or gas under normal conditions, it is possible to prepare a crystal structure analysis sample.
Further, when the crystalline sponge method is used, a crystal structure analysis sample can be prepared with a trace amount of an analysis target compound. Thus, by using the crystalline sponge method, it is possible to prepare a sample for crystal structure analysis efficiently even when an analysis target compound is a compound that is not easily available in a large amount (e.g., impurities in natural products or metabolites and the like).